Berlin (AP) - A new study on electric cars and climate appears - and attention is certain. Hardly any other environmental policy topic has been discussed more intensively for some time now. So how climate-friendly are you, the electric cars? A fact check.

CLAIM: E-cars have a better life cycle assessment than gasoline and diesel.

EVALUATION: Right - assuming you look at the entire lifecycle of a car.

FACTS: Following EU legislation, it's easy: electric cars do not emit a gram of carbon dioxide. Therefore, an automaker can polish up its average CO2 balance by an e-car in the fleet.

In fact, that with zero emissions is not right. First, there is the production: "In production, the electric car is initially worse off, which is mainly due to the energy-intensive battery production," explains Anika Regett. The scientist works at the Research Center for Energy Economics (FfE), her area of ​​expertise is Life Cycle Assessment. To make the rechargeable battery, relatively much power is needed. Its production causes emissions. How many depends on which sources of energy it is derived from.

Most studies assume 100 to 200 kilograms of CO2 emissions per kilowatt-hour (kWh) of battery power. The reason why some studies come to very different results when calculating material composition and power consumption is as follows: "The data for battery production is extremely difficult to obtain because it is confidential company data. Often you do not have access to it at all, "explains Peter Kasten, an expert on climate protection in transport from the Öko-Institut.

So assuming the average of 150 kilograms of greenhouse gases per kilowatt hour, so produced in the production of a standard e-car battery with 35 kWh power around five tons of greenhouse gases. If the emissions of the remaining production are added together, the various studies end up with values ​​between ten and twelve tons. For comparison: For vehicles with internal combustion engine - whether gasoline or diesel - expect experts on average with six to seven tons of greenhouse gases.

However, their ecological disadvantage in the production make up for the e-cars in operation. Almost all current studies come to this conclusion. The electric motor is "much more efficient" than an internal combustion engine, says Regett. "The electric car therefore has a lower energy requirement per kilometer." Their evaluation provides a life cycle assessment advantage over a petrol engine from about 50,000 kilometers driven. This calculation is based on a power mix with a share of 29 percent renewable energy sources. Other studies calculate the emissions advantage from driving performance of around 100,000 or even 150,000 kilometers.

One of the few studies that concludes that electric cars have no CO2 advantage over a diesel, among other things, is based on an above-average performance and thus particularly harmful to the climate of the e-car. It also assumes that emissions from power generation will remain constant over the next few years. That is unrealistic. In the current coalition agreement, for example, it is agreed that the share of renewable energies should be increased to 65 percent by 2030.

Regardless of the pure greenhouse gas balance, e-cars are regularly criticized: For the production of batteries, raw materials are used which are mined under ethically questionable and ecologically difficult conditions - such as lithium, cobalt and nickel. That's definitely a problem, explains Regett. That is why it is important to make battery production significantly more resource efficient. The further and recycling of the metals is also a relevant point: "The recycling is technically possible. But with lithium, for example, it is not yet economically worthwhile. »

Some experts also suspect that the use of electric cars could have a problematic "rebound" effect. This means that something ultimately leads to the opposite of what was originally intended for the measure. In this case, the assumption would be that the consumer uses the e-car, which he feels is environmentally friendly and for which he has spent a relatively large amount of money, more often than he would use his conventional car. For example, it replaces bicycle rides or public transport by electric car rides. Data from a 2014 study from Norway - a country with many electric cars - actually suggests this effect.

Nonetheless, the majority of experts in Germany are convinced of battery-powered cars. "In the car sector, I see no alternative to the electric car, as far as climate protection is concerned," summarizes Kasten. However, the turnaround alone is not enough, he emphasizes: "The basic requirement for climate protection in traffic is that we increasingly switch to much more efficient public transport - and reduce overall traffic."

FfE: Climate and resource effects of electric vehicles

Agora Verkehrwende: Carbon footprint of electric cars

Fraunhofer ISI: The current greenhouse gas emission balance of electric vehicles in Germany

Ifo: Coal Engines, Wind Engines and Diesel Engines: What Does the Carbon Footprint Show?

ICCT: Effects of battery manufacturing on electric vehicle life cycle greenhouse gas emissions (in English)

UPI: Ecological consequences of electric cars

Coalition Agreement of the 19th legislature